You really need it spelling out.  OK
You said the difference between a hi-mod and a standatd Evo is £2k (£3k less £1k). 
Here is the Cannondale Hi Mod Ultegra on the Cannondale website: It's $4260
http://www.cannondale.com/en/USA/Bi...parentid=9e0382fc-e3f9-4c61-9599-3aafb7a863b4
Here is the Cannondale Supersix Evo on the Cannondale website.  It's $3,200
http://www.cannondale.com/en/USA/Bi...parentid=4b6987a4-968e-4016-8156-95582340b7db
The specs are almost identical, bar a better wheelset on the Hi mod.  Same year, therefore directly comparable.
The difference in price is therefore $1,060.  Around £600-£700 depending upon the exchange rate.
Knock a bit more off for the better wheelset and you are down to about £500.
Why do I know this?  Because I was looking at buying one 6-9 months ago and so was a mate.  My mate went for the Evo (non Hi Mod) in the end and I went for something completely different.